Telephonic system.



No. 807,316. PATENTED DEO.12,1905.

'R.H.POLK.

TBLEPHONIG SYSTEM.

APPLICATION FILED JAN. 19, 1904.

3 SHEETS-SHEET 1.

alumni RMZe/a-JQ 77 @vihwaau No. 807,316. PATENTED DEC. 12, 1905.

R. H. POLK.

TELBPHONIC SYSTEM.

APPLICATION FILED JAN.19, 1904.

3 SHEETS-SHEET 2.

PATENTED DEC. 12. 1905 R. H. POLK.

TELEPHONIG SYSTEM.

APPLICATION FILED JAN. 19, 1904.

3 SHEETSTSHEBT 3.

Is a e UNITED STATES PATENT oFFIoE.

Specification of Letters Patent.

Patented Dec. 12, 1905.

Application filed January 19, 1904. $erial No. 189,693.

To (LZZ whom it may concern.-

- Be it known that I, RoBER'rH. POLK, a citizen of the United States, residing at Birmingham, in the county of J cfferson and State of Alabama, have invented certain new and useful Improvements in Telephonic Systems; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

It has heretofore been proposed to provide complete metallic service for two subscribers of a telephone system while employing but .two line-wires, the signal-circuits being grounded and the telephone-circuits extending through the two telephones, and my pres ent invention involves circuits making possible the full metallic service for two telephones with but two line-wires and a switchrelay for reversing the line-wires for the signal-currents.

The invention consists in certain novel constructions, combinations, and arrangements of parts, as will be hereinafter fully described and claimed.

In the accompanying drawings, Figure 1 represents a conventional diagrammatic show-' ing of the circuits and relays of a duplex system embodying the features of the present invention. Fig. 2 represents a modified form of the same. Fig. 3 represents a perspective view of the present improved switch-relay. Fig. 4 represents a similar view of a modified form thereof. Fig. 5 represents a, longitudinal vertical central section taken? through a springsupport, carrying a set of springs and an armature, the magnet being omitted. Fig. 6 represents a transverse vertical section taken on the plane of line 6 6 of Fig. 5.

In Fig. 1 of the accompanying drawings I have illustrated a switch-relay 1 of the common and well-known type employed for closing the central signal-circuit and the differ-' ential relay 2, which is employed for cutting out the relay 1 when the talking-circuit is closed, said relays being already known in the art. I have added my present improved relay 3 and the circuits employed in connection therewith for switching the line-wires out for signal purposes, and as the relays 1 and 2 are of well-known construction the same will not be set forth in detail further than is necessary for an understanding of the operation used in connection with the present improved relay 3.

The actual embodiments of the present improved relay are seen in Figs. 3 and 4, and, referring particularly to Fig. 3, the same consists of a suitable base 4, upon which rests an electromagnet 5, controlling a pivotallymounted armature 6, journaled in brackets 7 7 and carrying at its upper end an operating-finger 8, extending beneath a spring 9, connected by an insulating-block 10 with an upper spring 11, the springs 9 and 11 being connected at their opposite ends to and supported by an insulating-block 12, which block also carries a plate 13 beneath spring 9, a similar plate 14. above said spring, a similar plate 15 above plate 14 and beneath spring 11, and a plate 16 above spring 11, the free end of each spring 13, 14, 15, and 16 being provided with a contacting lug 17 for facilitating the effectual contact between the respective springs and their corresponding plates. It Will be observed that when the magnet 5 is not energized a circuit is closed from any suitable source of power through a conductor 44, connected with the rear end of plate 13, through said plate 13, spring 9, and conductor 27, connected with the rear end of said spring ing connected with the rear end of spring 11.

When the magnet 5 is energized, the armatii're 6 is drawn over to the pole of the magnet and the finger 8 is thereby raised, lifting the springs 9 and 11, breaking contact with plates 13 and 15 and makingcontact with plates 14 and 16, whereby a circuit may be closed through a conductor 71 and plate 14, with the rear end of which it is connected, spring 9, and conductor 27. A similar circuit may be closed through a conductor 7 6, connected with the plate 16 at its rear end through said plate, spring 11, and conductor 26.

The mechanism disclosed in Fig. 4 embodies exactly the same elements as are shown in Fig. 3, slightly differently arranged, but designed to accomplish the same function. In this figure 4"indicates a base carrying a magnet 5', whose armature 6 is pivotally carried by standards 7 7 said armature being formed with an operating-finger 8, designed to move an insulating-block '10, connecting springs 9 and 11, arranged edgewise with relation to each other in the same plane. The rear ends of plates 9 and 11 are carried by an insulating-block 12,'and plates 13 and 15' are arranged beneath the springs 9 and 11 and have their rear ends fixed to the block 12', and similar plates 14 and 16 are arranged above the plates 9" and 11' and have their rear ends fixed to the block 12. Each of the plates 13, 14, 15, and 16 is provided with a contacting lug 17 and the rear ends of the springs and plates are connected with conductors in a manner similar to the connections described with reference to the showing in Fig. 3. It will thus be seen that either of the constructions disclosed in Figs. 3 and 4 may be used and the same may be arranged in series of as many as may be desired for the various lines controlled.

In Figs. 5 and6I have illustrated a further form of switching-relay which differs only in detail construction from the disclosures in Figs. 3 and 4, the same principle being involved in all of the showings. In Figs. 5 and 6 I have illustrated a supporting or base plate 101, bent at its rear end, as at 102, for engaging the core of a magnet. (Not illustrated.) The front end of the base-plate 101 carries a loosely-mounted armature 103, which is secured in place by means of a bolt 104, passed therethrough and into the end of plate 101, the aperture in the armature through which the bolt 104 passes being of sufficient size topermit swinging of the armature. The upper end of the armature 103 is provided with a finger 105, carrying a plurality of insulatingblocks 106, engaging spring-switches 107. Each spring-switch 107 is fixed at its rear end in an insulating-block 108 and provided at its rear end with a conductor-receiving plate 109. A contact-plate 110 is arranged below each of spring-switches 107, and asimilar plate 111 is arranged above the same. Each plate 110 is provided with a contact-lug 112, designed to insure perfect contact between the same and the respective spring 107, and each spring 107 is provided with a similar lug 113 for insuring perfect contact between the same and the respective plate 111. As seen in Fig. 5, the respective plates 110 and springs 107 are normally on closed circuit or in contact with each other, while the respective plates 111 are held out of contact with the respective springs 107 by means of insulating-blocks 114, which blocks rise from the base-plate 101 and are each provided with a supporting annular shoulder and a reduced portion 115, which reduced portion penetrates the respective plates 110 and 107 for permittingthe plates 110 to rest upon said shoulder, the upper end of the reduced portion 115 supporting the respective plate 111. The front ends of the springs 107 project beyond the front ends of the plates 110 and 111 and rest upon the insulating-blocks 106, so that movement of the armature 103 is designed to swing the springs 107 out of contact with plates 110 and into contact with plates 111.

I have included in Fig. 1 a conventional showing of the structure fully disclosed in Fig. 3, and in Fig. 2 I have shown a modification of the switching-relay, which consists simply in a'separation of the sets of springswitches and the contact-plates therefor, one switch being actuated by the armature of one magnet and the other switch being actuated by the armature of another magnet. The operation of this structure is exactly the same as that of the relay seen in Figs. 1 and 3.

The utility of the present improved relay will be observed after a careful consideration of the circuits and operation of the elements disclosed in Fig. 1, in which 24 indicates generally a set of telephone receiving andtransmitting instruments, and 25 has general reference to a similar set, which sets of instruments have communication by line-wires 26 and 27 with the central office, at which point the relays 1, 2, and 3 are situated and at which point the battery 28 is also located. It is believed that the circuits will be best and most readily understood by description of the operation of the calling of the central oflice by the given telephones and the calling of the telephones by the office. Therefore, assuming that subscriber 24 wishes to be connected with some other line leading out of the central office, the receiver 29 is removed from hook 30, whereupon the said hook closes contact with the primary coil 31 of the induction-coil for the receiver 29, whereupon a circuit is closed as follows: through wire 32 to line 26, spring 11, plate 15, wire 33, wire 34, winding 35 of differential relay 2, wire 36, to negative battery 28, positive battery wire 37, winding 38 of relay 1, wire 39, winding 40 of relay 2, wire 41, plate 42, spring-switch 43, wire 44, plate 13 of relay 3, spring 9 of said relay, and line 27 to wire 45, communicating with transmitter 46. When this circuit is completed, the armature 47 of relay 2 will not be affected, as the current flowing through the differential windings thereof will produce counteracting flux, while the armature 48 of relay 1 will be operated and a circuit closed between spring-switch 49 and plate 50, whereupon the battery-current will divide off wire 37 onto branch wire 51, throughswitch 49, plate 50, wire 52, signal 53, which may be of the common and wellknown type, and through wire 54 to the negative side of battery 28. Upon signal at the central office the operator there plugs into the answeringjack 55 with plug 56, which puts positive battery from its tip 57 to line, whereupon the circuit is completed through wire 58, wire 34, winding 35 of relay 2, wire 36 to negative battery 28. This destroys the wire 34, wire 33, plate 15, spring-switch 11, line 26, wire 32, hook 30, primary 31, transmitter 46, wire 45, line 27, spring 9, plate 13, wire 44, spring 43, plate 59, wire 59, sleeve 60 of jack 55. through cord-circuit to positive battery. N ow,assuming that subscriber 25 wishes to call central, presuming, of course, thatreceiver 29 has been replaced on hook 30, leaving the line idle, receiver 61 is taken down, permitting hook 62 to close contact with primary 63, whereby the circuit'will be closed as follows: from hook 62 through conductor 64, line 27, spring 9, plate. 13, wire 44, spring 43, plate 42, wire 41, winding 40 of relay 2, wire 39, winding 38 of relay 1, wire 37, positive battery 28 to negative battery, wire 36, winding 35, wire 34, wire 33, plate 15, spring 11, line 26, wire 65, transmitter 66 to primary 63. They circuit of the signal 53 will thus be closed, as above described, and central answers in the same manner as just described. It will thus be seen that each telephone 24 and 25 has its complete circuit and means of controlling the signal while arranged on the same line, each telephone having full metallic service. Presuming that an outside subscriber has called for telephone 24, central plugs into multiple jack 67 or 68, putting positive battery on the tip 69 of plug 7 O, which follows wire 71,winding 72 of relay 3, wire 73 to negative side of battery 28 and to ground, energizing the magnet of relay 3 and operating the armature 6 of said relay, whereby the springs 9 and 11 will be lifted out of contact with plates 13 and 15 and into contact with plates 14 and 16. After this result has been attained the operator puts an alternating current from sleeve 74 to line over wire 75, which current flows to branch wire 76, plate 16, spring 11, line 26 to the winding of bell 77 and condenser 78 to ground. Now, assuming that the parts have been restored to their normal condition and that central wishes to call phone 25, the operator puts plug 56 in multiple jack 79, whereupon positive current flows from said plug through wire 58, wire. 34, winding 35, wire 36 to negative battery, actuating armature 47 and closing contact between spring 43 and plate 59. The operator next applies alternating current to sleeve 60, which flows through wire 59',

plate 59, spring 43, wire 44, plate 13, spring 9, line 27, the windings of bell 80, through condenser 81 to ground. Thus it will be seen that by simple operation of the relay 3 the line-wires may be reversed for the signal-current for telephone 24 and the signal of telephone 25 may be rung by current passed through the regular circuit without energiz ing relay 3.

An impedance-coil 82 is shunted past the windings of bell 77, and a similar coil 83 is shunted past the windings of bell 80, and these coils accomplish the very valuable function of preventing sounding of the bells upon the closing of the circuit of the opposite telephone by the removal of the receiver thereof due to the discharge of the condenser in line. In duplex circuits heretofore employed it is well known that when the receiver of one telephone is taken down the bell of the opposite telephone is tapped by reason of the discharge of the condenser of the first telephone therethrough. By the provision of the impedancecoil this tapping of the bell is obviated by reason of the fact that the condenser-discharge takes the path of least resistance and avoids the bell-windings. This obviates the objectionable feature-of one subscriber of a duplex line knowing each time the other subscriber calls central. I have found in practice that an impedance-coil of approximately two hundred and fifty ohms resistance gives the most satisfactory results when used in connection with a bell-winding of approximately one thousand ohms; but of course the relative resistance may be'altered as found preferable in any particular cases.

I employ a wire 84, by whichI tie the sleeve of all the jacks in common, so that battery will be on the sleeve of all jacks by the closing of the relay 2 in order that the operator may receive the busy test if she places the tip of a plug to the sleeve of any of the other jacks when an operator has a plug in any one thereof.

As above suggested, the disclosure in Fig. 2 embodies a modification of the structure disclosed in Fig. 1 in that therelay for reversing the line-wires is divided into two independent relays, as seen at 85 and 86, the same being adapted to operate in conjunction with the common forms of differential relay 87 and signal-relay 88. Relay 85 consists of a magnet composed of winding 89 and core 90 and an armature 91, adapted to be actuated thereby, said armature carrying a finger 92, designed to engage an insulating block 93 for actuating a springswitch 94, normally contacting with a plate 95 for causing the same to contact with plate 96, arranged above said spring-switch. The spring'94 and plates 95 and 96 are carried by an insulating-block 97 and connected at their rear ends with conductors 98, 99, and 100. Relay 86 is an exact duplicate of relay 85, and the same reference-numerals are applied thereto, the description applying equally well to both relays.

The circuits disclosed in Fig. 2 may be traced in a similar manner to the tracing of the circuits in Fig. 1, the windings of the relays 85 and 86 being in parallel for effecting synchronous action thereof, whereby the same result is obtained as if the relay 3 were being employed. It is therefore believed to be unnecessary to trace the circuits and describe the operation in detail with respect to the disclosure in Fig. 2, as the same would be simply a repetition of the detail description of the structure disclosed in Fig. 1.

While I have illustrated in detail an actual embodiment of my present improved switching-relay in Figs. 3 to 6, inclusive, of the drawings, I am not claiming the same in this application, but hereby expressly reserve my right to divisional application thereon, the present illustration being given in order that a full understanding of my improved telephone system may be had.

Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a telephone system, the combination with two sets of receiving and transmitting instruments, and a single metallic talking-circuit therefor, of an electric signal device on each side of said circuit, one of said signal devices being designed to be actuated by current supplied through one side of said circuit, and electrically-actuated means for reversing the sides of said circuit for supplying said current to the other of said signal devices.

2. Ina telephone system, the combination with a plurality of sets of receiving and transmitting instruments, of a plurality of sets of contact-plates spaced apart, a switch interposed between each set of plates normally contacting with one of said plates, afull metallic talking-circuit common to all of said sets of receiving and transmitting instruments and to one of the plates of each of said sets of plates, and to said switches, a grounded electric signal on each side of said circuit, one for each of said sets of receiving and transmitting instruments, and means for moving said switches for causing the same to contact with the opposite plates for reversing the line-wires for changing the signal-circuits.

3. In a telephone system, the combination of two sets of receiving and transmitting instruments, and a single metallic talking-circuit therefor, of an electric signal device on each side of said circuit, one of said signal devices being designed to be actuated through current supplied through one side of said circuit, a plurality of switches interposed in said metallic circuit, and a plurality ofplates also interposed in said circuit, and electric means for moving said switches out of contact with some of said plates and into contact with others of said plates for reversing the sides of said circuit for supplying current to the other of said signal devices.

4:. In a telephone system, the combination with a plurality of receiving and transmitting instruments, and a circuit common to the same, of an electric signal on each side of said circuit, a grounded conductor for each of said signals, a condenser interposed in the length of each of said grounded conductors, and a resistance shunted across each signal and forming a path for the discharge from the respective condenser.

5. In a telephone system, the combination with a set of receiving and transmitting instruments, anda circuit therefor, of an electric signal on one side of said circuit, a grounded conductor for said signal, a condenser interposed in the length of said grounded conductor, and a resistance shunted across said signal for forming a path for the discharge from said condenser independent of said signal.

6. In a telephone system, the combination with a plurality of receiving and transmitting instruments and acircuit common to the same, of a signal-coil on each side of said circuit, a wire grounding said coil, a condenser interposed in the length of said wires, and an impedance-coil shunted across each of said coils.

7. In a telephonic system, the combination with a plurality of sets of receiving and transmitting instruments, a circuit common to all of said sets, an electric signal for each of said sets connected with one side of said circuit and grounded at the other side, the winding of each signal being of comparatively high resistance, a condenser interposed between each of said signals and ground, and an impedance-coil of lower resistance shunted across the coil of each of said signals.

8. In a telephone system, the combination with a plurality of sets of receiving and transmitting instruments and a talking-circuit common to the same, of an electric signal for each of said sets, each signal having a circuit including one side of said talking-circuit and ground, a condenser interposed between each of said signals and ground, and means for preventing operation of the signals by the discharge from the condensers upon closing of the talking-circuit of either instrument.

In testimony whereof I hereunto afliX my signature in presence of two witnesses.

ROBERT H. POLK.

Witnesses:

W. B. HARPER, V. B. HILL.

IOC 

